Apparatus for manufacturing electrical insulation



Aug. 16, 1966 E. c. QUEAR ETAL APPARATUS FOR MANUFACTURING ELECTRICAL INSULATION Original Filed Nov. 21, 1958 5 Sheets-Sheet 1 Aug. 16, 1966 E, c. QUEAR ETAL APPARATUS FOR MANUFACTURING ELECTRICAL INSULATION 5 Sheets-Sheet 2 Original Filed Nov. 21, 1958 V: E a M smw m M5 4. m -J 6 7 m W 6 w mm r w m m W W H H m m MW Aug. 16, 1966 E. c. QUEAR ETAL 3,266,091

APPARATUS FOR MANUFACTURING ELECTRICAL INSULATION Original Filed Nov. 21, 1958 5 Sheets-Sheet 3 paf 717155 in m 51% THEIR ATTORNEY I I'- ll I'll L United States Patent 3,266,091 APPARATUS FOR MANUFACTURING ELECTRICAL INSULATION Eugene C. Quear, Pascal J. Eflin, and John M. Sell, Aprierson, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Michigan Original application Nov. 21, 1958, Ser. No. 775,398, noW Patent No. 3,214,621, dated Oct. 10, 1965. Divided and this application July 29, 1964, Ser. No. 392,981 1 Claim. (Cl. 1813) This invention relates to an apparatus for making electrical insulation of the type comprised of a length of insulating material having its opposite edges coated with a plastic material.

This application is a division of application Serial No. 775,398, filed on November 21, 1958, now Patent No. 3,214,621.

In the past dynamoelectric machine construction, a great deal of difficulty has been encountered in preventing the end turns of a winding from cutting through the slot insulation at a point located immediately adjacent the ends of the magnetic core on which the winding is wound. Where the windings are machine wound, the edges of the slot insulation are subjected to a shearing or cutting from the metal conductor and oftentimes are cut so that the conductor becomes shorted to the metal magnetic core.

In certain dynamoelectric machine constructions, the ends of the slot insulation have been strengthened by folding over a section of paper insulating material over the paper insulation and this extra layer is commonly referred to as a cult.

In contrast to the above described cuff construction, it is an object of this invention to provide an insulating material suitable for slot insulation that is formed from a sheet of insulating material such as kraft paper having its opposite edges coated with a plastic material such as nylon. With this construction, the paper may be applied directly to a slotted magnetic core with the plastic coating serving to prevent cutting through of the conductors and also serving to increase the over all stifiness of the paper.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a diagrammatic representation of a method of manufacture of the slot insulation of this invention.

FIGURE 2 is a side view with parts broken away of an extrusion die and feeding mechanism for applying the plastic coating to opposite edges of a sheet of insulating material.

FIGURE 3 is a sectional view taken along line 33 of FIGURE 2 and showing the insulating material passing through the extrusion die.

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 2.

FIGURE 5 is a perspective view of an armature of a dynamoelectric machine using the slot insulation of this invention.

FIGURE 6 is a sectional view of the slot insulation of this invention.

Referring now to the drawings and more particularly to FIGURES 5 and 6, the slot insulation of this invention comprises a sheet of insulating material 10 which has bonded thereto a coating of plastic material such as nylon. The plastic material coats one edge 12 of the insulating material 10 and has coated surfaces 14, 16 and 18. The insulating material 10 may be formed of any suitable elec- 3,266,091 Patented August 16, 1966 trical insulation such as kraft paper. It is noted that the insulating material 10 is coated along one edge, both on the top and bottom surfaces of the edge, and along the edge. In the sectional view of FIGURE 6, only one side of the insulating material is shown but as will become more readily apparent hereinafter, the opposite side of the insulating material 10 is coated in identical fashion with the edge shown in FIGURE 6.

Where it is desired to use the insulating material of this invention as slot insulation, other plastic materials may be used as edge coating. These materials include acetal, polycarbonate resins, polyethylene, polypropylene, vinyl resins, and acrylonit-r ile butadiene styrene copolymers (flexible). Where the insulating material is not folded in sharp angles, the plastic material may be of a more brittle character such as polystyrene, polymethylmethacrylate, cellulose nitrate, cellulose butyrate, acrylate resins, epoxy resins, and phenol-formaldehyde resins. All of the above materials with the exception of the phenolformaldehyde and epoxy resins are suited to be applied to the kraft paper by the extrusion method described hereinafter. The plastic material might also be applied by other methods than extrusion such as roll coating, brushing, spraying and edge dipping. Materials particularly suited to these latter methods are latices, hydrosols, organosols or solutions of plasticized vinyl, vinyl-acrylonitrile, acrylic and polyamide resins.

In FIGURE 5, an armature for a dynamoelectric machine is illustrated. This armature comprises a shaft 20 which carries a laminated core 21 formed with a plurality of slots 22. The laminated core is formed of the usual steel laminations held together in any conventional manner. The end face of the core may be fitted with a sheet of insulating material 24 which has cutaway portions conforming to the configuration of the slots. This sheet of insulation 24 may be secured to the end lamination of the metal core in any suitable fashion. The slot insulation 10 is fitted within the slots 22 of the magnetic core and it is noted that the coated edge of the slot insulation is positioned along the. end of the magnetic core. Thus, when the armature is wound with a winding including metal conductors, designated by reference numerals 26 and 28, it will be readily apparent that the coated edge of the insulating material will prevent the innermost conductors from cutting through the material over the areas designated 'by reference numeral 39. In other words, the plastic coating on the slot insulation will prevent the conductor from cutting through the slot insulation over the area immediately adjacent the end laminations of the magnetic core. The coated surface 18 of the slot insulation 10 will, of course, contact the metal laminations of the magnetic core. whereas the surfaces 14 and 16 will positively prevent the conductor from cutting through the paper insulation. It is to be appreciated that the slot insulation 10 has greater rigidity or stiffness when its opposite edges are coated with a plastic coating material. In FIGURE 5, only one end of the armature is illustrated but it is to be appreciated that the opposite end will be fabricated in a manner identical with the end illustrated in FIGURE 5, that is, the plastic coating will be positioned adjacent the end of the magnetic core of the armature in the same manner as that illustrated in FIGURE 5.

The method of coating the slot insulating material is illustrated diagrammatically in FIGURE 1 and is shown in greater detail in FIGURES 2 through 4. Referring now more particularly to FIGURE 1, the apparatus for coating the slot insulating material includes a screw type plastic extruding machine generally designated by reference numeral 34. This machine includes the usual hopper to which is fed granular plastic material. The hopper in turn feeds a chamber 36 (FIG. 2) fitted with screw 38 which forces the plastic material into a conical passage 40 formed in a block 41. The plastic material is fed from passage 40 into an extrusion die generally designated by reference numeral 42.

The insulating material 10 which is presented to the extrusion die is fed from a reel 44. The insulating material is pulled off the roll and through the extrusion die 42 by a pair of rubber pull-through rolls 46 and 48 driven by an electric motor '50. After the paper has been coated, it is wound onto another reel 52. The paper in passing between reel 44 and the extrusion die 42 passes through a heating station 56 which may include a chamber heated by electrical heating units. From the chamber 56, the insulating material passes through a paper guide 58 and thence into the extrusion die 42.

The extrusion die 42 as is better illustrated in FIG- URES 2, 3 and 4 is formed of a block 60 having axially extending passages 62 and 64. The passages 62 and 64 communicate with a central passage 66 formed in block 68. The block 60 has a transversely extending passage 70 which accommodates the paper insulating material 10 as it is being passed through the extrusion die. The passage 70 communicates with a pair of identical outwardly flared passages 72 and 74. One of these passages, 72, is illustrated in FIGURE 4, it being understood that the passage 74 has an identical configuration.

The die passage 74 is connected to passage 62 by means of a passage 76 whereas the opposite side of die passage 74 is connected with passage 64 via a passage 78. In a like manner, the die passage 72 is connected respectively with passages 62 and 64 via passages 80 and 32. The block 60, in addition, is formed with passages 84 which are adapted to receive electrical heating units for heating the extrusion die 42.

When plastic material is forced through the conical passage 40 and through passage 66 into passages 62 and 64, it is fed to opposite edges of the kraft paper 10 by means of passages 76 and 78 and 80 and 82. Thus, as the paper is pulled through the extrusion die 42, it is coated along its opposite edges to form a coating of the 4 type illustrated in FIGURE 6. It will be appreciated that this is a continuous process in that the coating is applied to the paper and the paper is then wound upon reel 52 where it is ready for use as slot insulation for parts of dynamoelectric machines.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

A die for directing plastic material around the marginal edges of a moving length of insulating material to form wear resistant marginal edges of substantially U-shaped cross-section along the marginal edges of said insulating material comprising, a slot formed in said die for receiving said moving length of insulating material, first and second passages disposed on opposite sides of said slotand extending transversely thereof, first and second die passages of a cross-section greater than said slot, each in communicating relationship with a respective edge of said slot and extending parallel therewith, a first pair of feeder passages extending transversely of said first and second passages and said die passages, each communicating between one of said die passages and a respective one of said first and second passages, and a second pair of feeder passages extending transversely of said first and second passages and said die passages, each communicating between the other one of said die passages and a respective one of said first and second passages.

References Cited by the Examiner UNITED STATES PATENTS 163,825 5/1875 Wallick. 1,952,469 3/1934 Snyder et al. 18l3 XR 2,687,553 8/1954 Calombo. 2,791,807 5/1957 Morin. 3,081,213 3/1963 Chinn 18-13 XR ROBERT F. WHITE, Primary Examiner.

L. S. SQUIRES, Examiner. 

